Preparation of sheet stock having longitudinal external weakenings therein and product thereof



June 4, 1963 E. J. RIPLING 3,092,470

PREPARATION OF' SHEET STOCK HAVING LONGITUDINAL EXTERNAL WEAKENINGS THEREIN AND PRODUCT THEREOF Filed July 29, 1959 3 Sheets-Sheet 1 l I20 /8 220 /6` (/8 L.20

E 2? U/ 1/ e ff [-rfLL/-a L-u--L/-H INVENTOR BY 7mm, f@ Qa# 5002.2,

ATTORNEYS June 4, 1963 E. J. RIPLING 3,092,470

PREPARATION OF SHEET STOCK HAVING LONGITUDINAL EXTERNAL WEAKENINGS THEREIN AND PRODUCT THEREOF 5 Sheets-Sheet 2 Filed July 29, 1959 35 l 40 4 52 F/@- 8 36 59 /7 V38 l l/ f T #2S i 3i/Bg; f 3 7 INVENTOR EDWARD J R/PL//v BY 7mm, PM@ 9A, .f Jam;

ATTORNEYS 3,092,470 K HAVING LONGITUDINAL EXT ERNAL June 4, 1963 E. J. RlPLlNG PREPARATION OF SHEET STOC WEAKENINGS THEREIN AND PRODUCT THEREOF 5 Sheets-Sheet 3 Filed July 29, 1959 NVENTOR EDwA RD J ILP/PL /NG ATTORNEYS United States Patent O 3,692,476 PREPARATEN @E SHEET STCK HVENG LQN- GTUDENAL EXERI'JAL WEAKENENGS THERE- iN ANB ERDUCT THEREE Edward 3. Kipling, Elossrnoor, lil., assigner to Continental Can Company, inc., New York, NE., n corporation of New Yori:

Fiied .iuly 29, i959, Ser. No. Stl 16 Ciairns. (Ci. .Z9-4.37)

This invention relates to the preparation ot sheet stock having lo-ngitud-inal external weakenings therein, and concerns particularly the preparation of a rolled stock having internal `discontinuities and external weakenings accurately located relative to one another.

it is known to produce metallic sheet and strip stock by rolling, and to subdivide it subsequent to rolling by slitting or a like severing operation. It is also known to produce sheet material having internal discontinuities by a rolling operation which reduces the billet thickness and extends its length. The billet is provided with one or more internal channels prior to iinal rolling, usually when the billet is rst prepared, with a content of an anti-welding or resist material which is likewise reduced in thickness and extended during the rol-ling, so that the resist serves to prevent welding at the discontinuity regions; wherewith the rolled strip produced is of laminate structure, comprising surface laminations of the billet metal separated by the residues of the resist material at the discontinuity regions, and Wit-h these laminations joined by integrating metal along the longitudinal edges and along longitudinal strips or spacers between adjacent discontinuity regions. When two or more such discontinuities are present, the strip is called multi-wide because it can be slit through the integrating metal or spacers and thus severed into a number of narrower strips each of which has a discontinuity therein and each of which has integrating metal connect-ions at its edges.

The word billet is employed herein to designate a body produced as a cast ingot, or by a body produced by bonding slabs through rolling or brazing. Correspondingly, the word lamination is employed herein to designate a llayer of the billet material which pro-vides a surface of the strip and is separated from a cognate lamination, toward the end of the rolling schedule, by the layer of residual anti-welding material.

The rolling operation, for converting the billet to the strip, usually results in a strip having camber with one or both edges departing from straight lines; and then, when one or more internal discontinuities are present, the edges thereof are no lon-ger straight and in the longitudinal direction of the rolling. Likewise, a widening of the stock occurs, and this widening is not uniform throughout the thickness and frequently the strip does not have parallel straight edges. Further, when an internal discontinuity is present, in practice the reduction of the original thickness of resist material may bring this to a thickness of 0.001 inch or less; and it is then difficult to discover the exact position occupied by a discontinuity in the rolled strip. When a strip is rolled multiwide, with or without internal discontinuities, it is frequently desired to be able to trim it to have parallel edges whether straight or not: and to be able to subdivide it into narrower strips with edges which are essentially parallel in each strip.

One use for such strips is in the making of tubular bodies, :by employing mechanical means or fluid pressure to cause the laminations to bend away from one another. Therewith the integrating metal connections at the edges of a single-wide strip remain as externally projecting tins having a thickness about twice that of :the laminations, in

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this illustrative example. The slitting of the multi-wide strip for producing the single-wide strips must be at accurately loca-ted longitudinal lines, because an intrusionv of the separating slit into or too close to a discontinuity will cause cracking and leakage of the tube produced. It is feasible to have the integrating metal relatively wide, to permit the slitting along the same at lines safely distant from adjacent discontinuity regions, and then to trim away excess after the tube has been opened: but this represents an uneconomic loss ot the metal thus trimmed away. That is, these integrating regions should be made as narrow as possible.

It has been found that the separation of a multi-wide strip into narrower single-wide vstrips can be efected by providing in the wide strip longitudinal lines of weakening; and that such weakenings can be produced at accu` rately preselected regions by preliminary treatment of the billet before its rolling is completed. This procedure is likewise effective with rolled strip stock, in providing weakenings by which irregular edge portions of the strip can be detached, to provide edges which are essentially straight for strip lengths of sheet to be cut therefrom and thus provide accurate guide edges from which such cuts can be made.

One of the objects of this invention is the process of preparing a billet having longitudinal surface irregularities lwhich become accurately positioned external weakenings in the wide strip roll-ed from the billet and permit longitudinal severance into narrower strips having their edges accurately located relative to one another.

Another object is the process of preparing a billet by providing an open longitudinal groove on its surface, with a weld-preventing or resist material therein, and then rolling to reduce the billet to the desired tina-l thickness and therewith closed the groove lwherewith the resist inaterial maintains the weakening effect introduced by the said groove.

A further object is the process of preparing a billet by providing longitudinal surface grooves at ditferent spacings from its center, and then rolling to reduce the billet to the desired nnal thickness and therewith provoking a diierential lateral spreading yacross the width as the strip is formed, wherewith the differential spreading compensates for `and coordinates with the diterential original spacing so that the groove residues in the final strip are spaced at positions determined in the billet before rollin-g.

A further object is the production of a multiwide strip having a plurality of internal discontinuities spaced fromV one another across the width of the strip by integrating metal connecting the surface laminations at the edges of the discontinuity regions, and with external weaker-rings accurately located at the integrating metal regions and spaced from the edges of adjacent discontinuity regions.

With lthese and other objects in View, as will appear in the course of the `following description and claims, illustrative practices are shown in the accompanying drawings, in which:

FIGURE l is an end View of an ingot prepared according to this invention;

FIGURE 2 is an end view on a larger scale, of part of a multi-wide strip prepared from the ingot of FIG- URE 1;

FIGURE 3 is an end view of a modified form of billet;

FIGURE 4 is .an end View on a larger scale of a part of a multi-wide stript prepared from the billet of FIG- URE 3;

FIGURE 5 is a perspective view of two slabs for forming a billet; v

FEGURE 6 is a diagrammatic view, at greatly enlarged scale, of a billet groove =with resist material therein', and

showing in dotted lines the condition after a partial rolling;

FIGURE 7 is a diagrammatic View, corresponding to FIGURE 6 ibut showing the, weakening present after rolling;

FIGURE 8 is agdiagrammatic view illustrating a manner of separating the strip;

FIGURE 9 is a perspective view showing removal of an edge portion from a strip;

` FIGURE 10 is a conventionalized showing of an apparatus for ilexing and notch breaking a section of the strip of FIGURE 9;

FIGURE 11 is a perspective view of a conventionalized apparatus for longitudinally ripping the strip of FIG- URE 9.

An in-got may be prepared by casting a metal, e.g., steel or aluminum in a mold, to provide the body B in FIG. l.v Incidental to the casting, or by subsequent operation thereafter, longitudinal channels 10 can be provided and lilled with an anti-Weld or resist material appropriate to the metal, the temperature to which it is subjected during the rolling schedule, and the purpose for which it is to be used. Finely powdered aluminum oxide, titanium oxide, silicon oxide, talc, graphite, and like reractories are useful with hot rolling schedules; noting that graphite should not be employed if its presence will damage the product, e.g., by electrochemical effects or by the creation of undesirable carbide concentrations. Such an ingot may be made of a transverse dimension accepted by the rolls to be employed: and therewith may have a number of the core channels '10 spaced across its width: more than three being indicated in FIGURE l, noting that each core channel is to provide yan internal discontinuity in the multi-wide final strip. The metal above `and below the core channels in' FIGURE 1 is integrated by metal connections 11, 12 at the longi- #tudinal edges `and between adjacent channels.

According to this invention, the ingot body B of FIG- -ure l1 also has longitudinal grooves 14 provided therein, being present opposite the intermediate integrating connections 12. Iln FIGURE 1, such are shown at both top Iand bot-tom faces of the ingot; but it will be understood that employment of only one such lgroove opposite each connection 12 is comprised in the invention. Such ygrooves may tbe formed by mold wall projections, or can be later cut or impressed mechanically.

Upon rolling the ingot of FIGURE l, the `grooves 14 are closed to -give essentially smooth surfaces in the nal multi-wilde strip, -as shown in FIGURE 2, where the metal laminae 15, -16 are separated by the residues 17 of the cores, and are connected at the edges of such residues by the integrating residues 1S of the connections 11, 12 of FIGURE l. The grooves have been closed, but their walls begin to abut along planes essentially normal to the ingot surfaces and hence lnoV substantial welding pressure is being exerted therebetween. It is preferred to coat one or both Walls of each `groove with an adherent coating 19 of resist or anti-welding material, so that the same is present when the 4groove becomes closed: during rolling the dimension of this resist material, in the transverse direction of the ingot, remains essentially the same, but its dimension in the direction between' the rolled surfaces of the'ingot is reduced essentially `in proportion to the reduction of the metal stock andof the resist material in the channels.

' During the course of the rolling, the: over-all thickness is decreased, `and therewith the/ingot becomes a strip S, FIGURE 2: with an increase of width of up to 14 percent dependent upon'the Amaterial and the treating and rolling schedule, and `amounting lto say 1/2 percent Iwith a long schedule of low reductions and up to 14 percent with a schedule of very heavy reduction per pass: in practice a spread of 4 to 5 percent is a desirable amount for an economical rolling schedule. The yingot B tends to spread more at one or more planes between the surfaces than at its top and bottom surfaces, noting that the friction between each roll and the surface cont-acted thereby act to restrict surface spreading at the surface planes X. The spreading may differ at successive planes from the surfaces toward the median or central plane: e.g., when the `reduction per pass is small, the spread adjacent the surfaces is greater than that at the median plane; while with high reduction per pass, `the sp-read at the median plane M is usually greater than at any plane between the median and surface planes. Therewith the residues 20 of the grooves tend to shift from positions at right angles to the surfaces to positions at acute angles, the angle increasing from the center of width toward rthe edges, as shown in FIGURE 2; but with the inner edge of each groove remaining alined with its `associated integrating metal or spacer 18. In general, if each groove has an original depth of about one-third the thickness of the ingot, each residue 20 is less than one-third of the total thickness of the strip, and two opposed grooves will be separated by a distance of about half the total thickness measured through the integrating metal. As a specific example, the ingot B of FIGURE 1 may have la thickness of 11/2 inches, with each core channel 13 0.060 inch thick and filled with resist and having the integrating metal connections about 0.125 inch wide, and with the grooves 14 each shaped as a 45 degree V and cut 0.350 inch deep with a resistrcoating 19 4about 0.020 inch thick; then upon rolling, the integrating connections widen during rolling to 0.130 to 0.150 inch, dependent upon the rolling schedule, when the strip has been reduced to a total thickness of 0.025 inch comprised at the discontinuity regions of two metal laminations l5, 1.6 which lare each 0.012 inch thick and separated by la resist residue 17 which is 0.001 inch or less thick, and having the integrating connections 18 0.025 inch thick from `face to face of the Strip; wherewith the groove residues 20 .are about 0.005 to 0.010 inch in the transverse direction of the strip `and extend into the integrating metal for about 0.0025 to 0.005 inch each. It will be noted that therewith the distance between opposed groove residues is about 0.017 inch, with each residue separated by about 0.062 inch from lthe adjacent edges of the core residues 17.

Y It has been yfound that such grooves, FIGURE 1, with an included angle of 45 degrees, are elective, when such alined grooves are formed in the upper and lower surfaces and 'to a depth of 23 percent of the billet thickness for each, or 46 percent in all. During Vthe initial rolling passes, and with the metal being spread laterally to close the open ygroove volumes, the metal between the roots of -a pair or such grooves is not reduced proportionately to the reduction of the metal at points intermediate two pairs of grooves. For example, a customary rolling procedure results in the residues of these Agrooves being each about 1S percent of the total thickness of the strip when reduced to nal gauge, or 316 percent for the two. In general, the notches should originally have included angles less than degrees, `and more than `about 20 degrecs -when spray coating thereof is employed: preferably the tangle should be between 25 and 75 degrees, noting that the angles of successive `grooves in a single Ibillet may dier. Similarly, it is preferred to have the depth of each groove between 10 and 25 percent of the billet thickness, -again noting that `all grooves on a single billet need not have the same depth.

In the form of FIGURES 3 `and 4, fthe billet B illustratively has `four cores 10, two being disposed symmetrical-ly to the longitudinal central upright plane indicated by line 2.5, with two cores between such plane and each longitudinal edge. Alined withrthe integrating connections 12, 4in FIGURE 3, are the pairs of grooves 14a, 14h, 14C. In the form` of FIGURE t3, the grooves 14b, 14C are tilted reltaive to longitudinal upright planes so that each `groove has its side which is nearer the center plane 25 at .a greater angle to the billet surface than the side which is farther yfrom the center; and for each successive groove the tilting is greater `for a rgroove near the edge than for a groove nearer the center: the tangle of tilt likewise being coordinated to the material and treatment schedule. Expressed in another way, when the rolling schedule produces a greater spread at the intermediate planes P than at the surfaces X, the bisectors of the root angles of the illustrated V cross-sections of the grooves can be at successively greater `angles to the surfaces of the billet, from its center of width toward its lateral edges, as indicated by the greater angularities D of the bisector lines Mm than the angularities C of the bisector lines idk in FIGURE 3, with the Ibisectors of each pair of grooves in the illustrative form intersecting one another at the median plane M and at a point closer to the center plane 25 than the roots of 'the V sections from this center plane. Illustratively, the tilt angles C may be 2 to 4 degrees and the tilt angles D 6 :to 12 degrees, with 45 degree grooves in an 8 inch billet.

Furthermore, if the rolling schedule is such that the spreading at the median plane M is significantly greater than that at intermediate planes P, a further compensating eect can be provided by varying the locations of the groove roots relative to the adjacent cores l0. Thus, in FIGURE 3, the longitudinal upright central geometric plane of line 25 intersects the med-ian plane M at equal distances from the adjacent cores lil, and passes through the roots of the central grooves 14a: that is, if the spacing between adjacent edges of the cores is 0.125 inch, the plane 25 is 0.0625 inch from each. lllustratively, the several core spacings are 0.125 inch, and the longitudinal upright geometric planes 26k, 26m intersect the median plane M at distances of 0.0625 inch from adjacent cores It?. The longitudinal upright geometric planes 25k, 25m through the groove roots of .the respective pairs of grooves 14-b, 14C are spaced laterally outward from the adjacent planes 26k, 26m. Thus a plane 25k may he 0.020 inches from its adjacent plane 26k; and a plane 25m 0.040 inch from its adjacent plane 26m. These val-ues are proper for a rolling schedule by which the total lateral spread, or gain of width, is about 4 percent at the median plane M. It will be understood that the expression geometric is employed to designate a plane or surface of reference, which need not be a superlicies or boundary yface of a part.

Upon rolling the billet B of FIGURE 3, the grooves are closed by the transverse displacement of metal of their walls, and the resist material is therewith abutted at both sides lby metal which is held against welding by this resist material. As the rolling progresses, the residues are at right angles to the rolled surfaces of the strip upon completion of the rolling. Since the widening of the billet is essentially zer-o at the surfaces X and is greater between these surfaces, in a fashion symmetrical relative to the median plane M, the two residues 20a (FIGURE 7) of a pair therewith lie in an upright longitudinal geometric plane 3S and bythe greater spreading at the med-ian plane M than at the intermediate planes P for the specified schedule, the integrating metal connections 12 move laterally outward relative to the groove residues, so that the roots of residues 20a of the pairs of grooves lie in respective upright geometric surfaces which pass through the integrating metal connections 18 of the strip at uniform and predeterminable distances from the adjacent edges of resist residues `1'7, eg., exactly midway between two such residues.

The course of the early flow of metal during rolling, to close the grooves of a body B, FIGURES 1 and 3, is shown in FIGURE 6, in which a part of the body B has a groove 20m therein, with a coating of resist material 19 on one wall 27 thereof, while the other wall 28 is illustratively bare. During the initial part of the rolling, eg., hot rolling, the surface 29 is depressed to a level 29a by a reduction of d1; wherewith the metal iiows laterally to fill the groove, with 'the metal of wall 27 carrying the resist material with it and thus bringing it to abutment by the met-al ii-owing from the wall 28. This phase of rolling results in a smooth surface formed .by metal and resist material: it being noted that surface met-al of the body between the grooves is being extended longitudinally by rolling essentially in proportion to the reduction in height lfrom surface level 29 to surface level 29a as a fraction of the thickness of the billet; Whereas the reduction d2 below the original root of the groove is less than the reduction d1. Therewith, while the distance from the root of a groove to an adjacent core `lltl may be less inthe original ingot than the distance between the roots of the grooves 0f a pair, the reduction to strip thickness leaves the lateral core spacing essentially unchanged, eg., 0.125 inch, while the total strip thickness of 0.025 inch now has groove residue weakenings extending from its surfaces and spaced 0.0018 inch apart, which is less than the distance from either weakening to the adjacent core residue.

The `eect of the external longitudinal weakening is illustrated in FIGURE 7, in which the body of strip S has groove residues 20a extending from its surface Ifor about one-third of the thickness each. When 'tensile forces are applied, the resulting pattern (indicated by the dotted lines) will contain a great concentration of stresses at the upright plane 35 of the residues 20a rather than in the rest of the integrating metal 1S and in the laminated regions above and below the resist residues t7. A like concentration occurs -when bending forces are exerted, or shearing forces exerted along the plane of the residues 20a. Therewith the metal at such plane yields, and breakage thereat can be accomplished without significant yielding at other places.

The billet B may be rformed with cores in other ways, including those taught in the Valyi et al. United States Patent No. 2,375,334, and provided with external longitudinal grooves. Thus, in FTGURE 5 are shown two like slabs 30, 3l which may be formed by extruding aluminum which provide longitudinal ribs 32 at one surface and longitudinal grooves 33 at the other surface and alined with the ribs 32. The ribs 32 define channels 34 which can be filled with a slurry of the resist material and baked. The exposed edge surfaces of the ribs 32 are cleaned of any Aadherent resist. The upper slab 30 is then inverted and placed over the lower slab 3l so that the ribs 32 abut. The assembly may be initially maintained by edge welding: `and hot rolling is then employed to secure bonding between the abutting surfaces of the ribs 32. Surfaces of the grooves 33 may be provided with resist 119 before or after the assembly. The assembly is then subjected to the polling schedule, for producing a strip S as in FI!"- URE 2 or 4.

In FIGURES 3 and 4, the edge grooves 14e and their residues 2da permit the production in the final strip of a break along an upright surface 3S (FGURES 8 and 9) ywhich is parallel to the edge of the adjacent resist 17 and at a predeterminable distance therefrom, regardless of camber of the strip or local irregularities of the strip edge. The narrow edge piece can then be brokenaway, and forces applied at distances measured from this guide edge. AIt will be noted that this break is accomplished independently of the presence of the illustrated resist residue: and that a solid sheet or strip may likewise have its edge detached, or be separated into narrower strips. Thus in FIGURE 8, the strip S has had an edge portion 3d thus removed; thereupon the width of the adjacent single-wide portion S-l can be closely determined, andV the multi-wide strip supported at the area of the next singleiwide portion 5 2, as indicated by the force arrow 37 and this portion S-Z held by a force 33 against its upper surface. A bending force, indicated by arrow 39 can then be exerted upon the upper surface of the portion S41 so that the latter bends downward toward the position shown by the `dash lines, hinging about the longitudinal weakening at the plane 40 through the residues 2da, 20a of PGURE 7, and breaking.

Such separation of the narrow strips from one another can be accomplished in other ways. In FIGURE 9, the

strip-S has the edge weakening 35 as before. A break isstarted at ioneend of the strip, and the edge portion 36 can then be `torn away, noting that the severance is con` trolled by and follows the surface represented by the line 35 in FIGURES 7, 8 and 9, at the predetermined distance from the edge of the nearest residue 17.

. The multi-wide remainder of the strip S, shown as sixwide in FIGURE 9, may now be cut transversely, e.g., at lines 41 to provide sections which can then be moved between breaker :rolls 42 which act to flex and bend the section T, wherewith the material at the surfaces containing the residues 20a of FIGURE 7 are stressed beyond recovery, and breakage is produced, between the narrow strip portions V of the section T at accurately located places determined by the residues 29a. The breaker rolls 42 are positioned in upper and lower sets in FIGURE l0, with the lower tangent of the upper set of rolls located below the upper tangent of the lower set, so that the section T, shown by dotted lines in FIGURE l0, is successively flexed in opposite directions through half angles of 45 `degrees `or through bends of short 4radii established by rolls, until it separates. When the broken sections V are so narrow that they cannot contact three rollers to assume the flexing and continued movement in the apparatus, they may be controlled during passage between the rolls 42 by the belts 45, which may be relatively loose so that the panels formed by the successive narrow strips in hinging about the longitudinal weakenings can retain relative ilatness without conforming to the rolls 42 in passage therebetween. With Wider strips V, the belts 45 may be omitted.

The narrow strips may also be produced as an incident of ceiling. In FIGURE ll, the strip S is delivered between the shafts Sii, d `of two take-up reels. The end of strip S is split along the individual lines 35 between the narrow strips S41, S-Z, S-S, 8 4, S-S and S-6 thereof; and the ends of alternate strips, illustratively strips S-l, S-3 and S-S, are connected tothe upper driven shaft 50, and the ends of the other strips, illustratively strips S-2, S4 and S-6, connected to the lower driven shaft 51. As the shafts rotate in the direction shown by the arrows, the individual strips are Wound onto the shafts to form the rolls R-l, R-2, R-3, R-4, R- and R-6; noting that any two rolls on each shaft are spaced axially by the width of the strip being wound on the other shaft in alignment with such space, and that the peeling or shearing `effect as the narrow strips are pulled along their lines `of longitudinal weakness while the general area of each strip is being supported by the contactA therewith of the already-wound part of that strip.

In practice, it has been found that notches of V crosssection, with the roots having angles of about l()` to 55 degrees, are satisfactory. Such a notch with an inner or root angle fof 45 degrees can be coated with anti-welding material along `one wall, to a thickness of 0.005 to 0.020 inch by ilame spraying, by deposit and baking of a slur-ry of the resist material, or by powder deposit into a sharpangled groove followed by peening the outer lips together to enclosethe powder. When sharper root angles, eg., 8 degrees, are employed, the lateral spreading of the metal to close the groove usually causes a thickened section of the resist material to form adjacent the root of the notch; grooves with inner or root angles `of over 60 degrees did not close regularly but tended to become shallower; whereas angles within the stated range cause the resist material to provide a weakening of substantially constant width in the direction from side to side of the rolled strip, and voften with a fairly sharp angle at its inner edge.

The lateral closure of the grooves provides smooth rolled surfaces on the multi-wide strip. For example, with a billet originally 1.50 inches thick, and having alined pairs of notches `of 45 degree V section and 0.35 inch deep, no visible indentations were present on the rolled surfaces upon reduction to 0.25 inch thick. Upon rolling 8 billets to an rover-all thickness of 01.018 inch, the differential lateral spreading was found to vary with the billet material, its heat treatment before and during rolling, and the rolling schedule, that is, the number of passes and the reduction per pass.

It is obvious that the illustrative practices are not restrictive, and that the invention can be employed in many ways within the scope of the appended claims.

. What is claimed is:

l. The method of preparing narrow strips of material each having an internal discontinuity between surface laminations, the laminations being connected at the lateral edges of Ithe discontinuity, which comprises preparing a billet of the material with a plurality of internal longitudinal channels spaced laterally from one another and from the longitudinal edges of the billet by portions of solid metal extending from face to face of the billet, said channels containing extensible Weld-preventing material, said billet having a plurality of longitudinal external grooves at a roll-engaging face thereof, each of said grooves being located opposite one of the said solid metal portions, the parts of said solid metal portions beneath the roots of said grooves being effective to maintain integrity of the billet from side to side during rolling, placing a weld-preventing material on a wall of each groove, rolling the billet longitudinally whereby to cause lateral closure of the grooves and reduction of the total thickness of the billet to that desired for the narrow strips wherewith the dimension of the residues of said weld-preventing material in the direction of the thickness of the strips is reduced coordinately with the reduction of such total thickness, and then applying forces to the rolled product whereby to over-stress and effect separation along the lines of said residues of the weld-preventing material applied to the groove lwalls and thereby separate the rolled product into a plurality of narrow strips.

2. The method as in claim l, in which the longitudinal grooves are provided at opposed surfaces of the billet, with said grooves yalined in pairs, whereby the rolled product has the residues of the weld-preventing material of said pairs of grooves alined and constituting parallel longitudinal regions of weakness in said rolled product.

3. The method as in claim 2, in which the rolled product is subjected to repeated flexings in opposite directions to effect the separation.

4. The method of preparing narrow strips of material each having an internal discontinuity between surface laminations, the laminations being connected at the lateral edges of the discontinuity, which comprises preparing a billet of the material with a plurality of internal longitudinal channels spaced laterally from one another and from the longitudinal edges of the billet by portions of solid metal extending from face to face of the billet, said channels containing extensible weld-preventing material, said billet having a plurality of longitudinal external grooves at a roll-engaging face thereof, each of said grooves being located opposite one of the said solid metal portions, the parts of said solid metal portions beneath the roots of said grooves being effective to maintain integrity of the billet from side to side during rolling, said grooves being spaced differentially across said roll-engaging face so that two adjacent grooves near an edge are at a different spacing than two adjacent grooves near the center of width, placing a weld-preventing material on a wall of each groove, rolling the billet whereby to cause lateral closure of the grooves and reduction of the total thickness of the billet wherewith lateral spreading of points spaced across the width occurs during rolling, terminating the rolling when the `lateral spreading has brought the residues of the grooves to predetermined spacing thereof, and applying forces to the rolled product ywhereby to over-stress and effect separation along the lines of the groove residues.

5. The method as in claim 4, in which a wall of each groove receives a coating of weld-resisting material prior to rolling.

6. The method as in claim 4, in which two opposed surfaces of the billet have longitudinal external grooves of V shape, arranged in pairs with the points of the Vs located in a surface at right angles to said opposed surfaces.

7. The method as in claim 4, in which the grooves have V cross-sections, said cross-sections of the grooves are til-ted relative to one another, with the grooves adjacent the lateral edges of the billet having a greater tilt than grooves nearer to the center of the width thereof.

8. The method `of preparing narrow strips of metal each having an internal discontinuity between surface laminations, said laminations being integrally connected at the edges of each strip, which comprises preparing a billet having internal longitudinal cores of extensible weld-preventing material, said cores being alined transversely of the billet and separated by metal spacers integral with the surface metal of the billet, said billet also having external grooves in roll-contacting surfaces of the billet and alined with the said metal spacers, the metal of said spacers beneath the roots of the grooves being effective to maintain integrity of the billet from side to side during rolling, each groove having a coating of Weldpreventing material on a wall thereof, rolling the billet whereby to reduce its thickness to that desired for the strips wherewith the grooves are closed by lateral spreading of adjacent billet material to provide smooth surfaces and -with the residues of said coating extending inward from the respective surface, and applying forces to the rolled product whereby to over-stress and effect separation into narrow strips along the lines of the groove residues, each strip having an internal discontinuity from the residue of a said core.

9. The method asin claim 8, in which grooves are provided in -opposed surfaces of the billet, the grooves being alined in pairs along geometric surfaces intersecting said opposed surfaces and each passing through a said spacer.

10. The method as in claim 8, in which the grooves are of V cross-section, and the cross-sections of the grooves are relatively tilted, the tilt being progressively greater from the center y.of width toward the edges.

11. 'Ehe method .as in claim 10, in which the grooves are provided at the opposed surfaces of the billet, and arranged in pairs, with the points of the Vs of each pair lying in a geometric surface normal to said opposed surfaces and passing through a said spacer.

12. The method as in claim 8, in which a pair of alined grooves are provided between an edge of the billet and the edge of .the adjacent core, whereby to provide in the rolled product a longitudinal weakening parallel to the edge of the residue of said core along which may be severed a strip at a predetermined distance lfrom the residue of said core.

13. The method of preparing a strip having a plurality of internal longitudinal discontinuities spaced across its width and with longitudinal weakenings in planes intersecting the body material between :the discontiuities, which comprises preparig a billet having -a like number of longitudinal discontinuities l'therein and with billet metal extending as spacing regions between each two of said dis- '.'continuities, said discontinuities containing extensible weld-preventing material, and including the .forming ou an external roll-contacting surface of the billet of longitudinal ygrooves spaced at unequal intervals across the width of the billet, the metal beneath the roots of the grooves being effective to maintain integrity of the billet from side to side during rolling, the spacing being greater toward the side edges than near the center, providing antiwelding material in the grooves, and rolling the billet so that the thickness is reduced to that of the desired strip wherewith the anti-welding material extends longitudinally in proportion to the decrease in billet thickness and therewith causes the strip to have a llaminated structure at the said discontinuities, wherewith the said grooves become closed :during the rolling and the anti-welding material therein provid-es longitudinal weakenings along the strip, and wherewith the lateral spreading of the billet during rolling causes the weakenings to be presented at uniform ,intervals across the width of the strip and each opposite the rolled residue of -a said metal spacing region.

14. The method of preparing narrow sections of metal each having `an internal discontinuity between surface laminations, -said laminations being integrally connected at the edges of each section, which comprises preparing a billet having internal `cores of weld-preventing material extending along its length, said cores being alined transversely of the billet and separated by metal spacers integral with the surface metal of the billet, said billet also having external grooves in roll-contacting surfaces of the billet and alined with the said metal spacers, the metal beneath the roots of the grooves being effective to maintain integrity of the billet from side to side during rolling, rolling the billet whereby to extend its length and reduce its thickness to that desired for the sections wherewith the external grooves are closed by lateral spreading of adjacent billet metal to provide smooth surfaces, and applying forces to the rolled product at laterally spaced regions thereof whereby to over-stress and effect separation into narrow sections along the lines of the groove residues, each section having an internal discontinuity from the residue of a said core.

15. An article of manufacture which is a billet of rollable metal and having metal surface portions separated in longitudinally extending regions of the billet by a longitudinal internal channel at each such region and having integrating longitudinally extending metal spacer portions between each two adjacent regions, and a plurality of external longitudinal grooves in a roll-contacting surface of the billet, each said groove being spaced laterally relative to and between the lateral edges of two adjacent internal channels and extending into the respective metal spacer portions, with a Wall of each groove having a coating of weld-preventing material.

y16. An article of manufacture which is a billet of rollable metal and having metal surface portions separated in longitudinally extending regions of the billet by a longitudinal internal channel at each such region and having integrating longitudinally extending metal spacer portions between each two adjacent regions, and a plurality of pairs of external longitudinal grooves in the roll-contacting surfaces of the billet, each pair of said grooves being spaced laterally relative to and between the lateral edges of two adjacent internal channels and extending into the respective metal spacer portions, with a wall of each groove having a coating of weld-preventing material, each said groove being of V-shape `and having the bisectors of the angles between the groove walls located at acute angles to the said opposed surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 140,762 Bolton July 15, 1873 1,209,949 Dodds Dec. 26, 1916 1,926,320 Trembour Sept. 12, 1933 2,079,213 Ingersoll May 4, 1937 2,215,933 Offutt Sept. 24, 1940 2,375,334 Valyi May 8, 1945 2,377,857 Belanger lune l2, 1945 2,423,810 Goulding July 8, 1947 2,766,514 Adams Oct. 16, 1956 2,851,770 Fromson Sept. 16, 1958 2,986,810 Brick June 6, 1961 

1. THE METHOD OF PREPARING NARROW STRIPS OF MATERIAL EACH HAVING AN INTERNAL DISCONTINUITY BETWEEN SURFACE LAMINATIONS, THE LAMINATIONS BEING CONNECTED AT THE LAT ERAL EDGES OF THE DISCONTINUITY, WHICH COMPRISES PREPARING A BILLET OF THE MATERIAL WITH A PLURALITY OF INTERNAL LONGITUDINAL CHANNELS SPACED LATERALLY FROM ONE ANOTHER AND FROM THE LONGITUDINAL EDGES OF THE BILLET BY PORTIONS OF SOLID METAL EXTENDING FROM FACE TO FACE OF THE BILLET, SAID CHANNELS CONTAINING EXTENSIBLE WELD-PREVENTING MATERIAL, SAID BILLET HAVING A PLURALITY OF LONGITUDINAL EXTERNAL GROOVES AT A ROLL-ENGAGING FACE THEREOF, EACH OF SAID FGROOVES BEING LOCATED OPOSITE ONE OF THE SAID SOLID METAL PORTIONS, THE PARTS OF SAID SOLID METAL PORTIONS BENEATH THE ROOTS OF SAID GROOVES BEING EFFECTIVE TO MAINTAIN INTEGRITY OF THE BILLET FROM SIDE TO SIDE DURING ROLLING, PLACING A WELD-PREVENTING MATERIAL ON A WALL OF EACH GROOVE, ROLLING THE BILLET LONGITUDINALLY WHEREBY TO CAUSE LATERAL CLOSURE OF THE GROOVES AND REDUCTION OF THE TOTAL THICKNESS OF THE BILLET TO THAT DESIRED FOR THE NARROW STRIPS WHEREWITH THE DIMENSION OF THE RESIDUES OF SAID WELD-PREVENTING MATERIAL IN THE DIRECTION OF THE THICKNESS OF THE STRIS IS REDUCED COORDINATELY WITH THE REDUCTION OF SUCH TOTAL THICKNESS, AND THEN APPLYING FORCES TO THE ROLLED PRODUCT WHEREBY TO OVER-STESS AND EFFECT SEPARATION ALONG THE LINES OF SAID RESIDUES OF THE WELD-PREVENTING MATERIAL APPLIED TO THE GROOVE WALLS AND THEREBY SEPRATE THE ROLLED PRODUCT INTO A PLURALITY OF NARROW STRIPS. 